The invention relates generally to a method for controlling the operation of an internal combustion engine. More especially, the invention relates to a method for controlling an internal combustion engine on the basis of information related to combustion chamber pressure fluctuations. In particular, the invention relates to a method for controlling an internal combustion engine on the basis of fluctuations of cyclic variations of the combustion chamber pressure transduced from the rotational speed characteristics of the engine and possibly from other operational parameters of the engine.
The signal which relates to the roughness of engine operation, sometimes called quiet-running signal, and which is used as the basis for the known control method depends on the fluctuations of the combustion chamber pressure. When this signal is taken from the output shaft of the engine, it is subject to damping of varying intensity, for example due to the different transmission ratios selected, for example in a manual transmission. In order to obtain a uniformly useable signal for control purposes, the set-point value with which the actual fluctuations are compared would have to be adapted to the varying degrees of damping.